A hopper is a chamber for storing bulk commodities such as grain, rock, coal, biomass etc. The bulk commodities are typically loaded into a hopper through an inlet aperture at the top of the chamber and discharged through an outlet aperture in the bottom of the chamber. Due to the arrangement of the outlet, bulk commodities discharge through the outlet under the force of gravity. The discharging process is controlled by using a discharge system to open and close the outlet aperture when required.
A hopper may be a free-standing container or it may be combined with other apparatus. For example, a hopper may be incorporated in a vehicle.
A hopper wagon is a type of freight railway vehicle for transporting bulk commodities. The hopper wagon comprises a hopper wagon body with a hopper chamber for storing bulk commodities. The hopper wagon body is supported by an underframe. Bogies may be coupled to the underside of the underframe to allow the hopper wagon to move along the railway track. The bulk commodities are loaded into the chamber through an inlet aperture and discharged through at least one outlet aperture. The inlet aperture is conventionally formed in the top of the hopper wagon body whilst the at least one outlet aperture is conventionally formed in the bottom of the hopper wagon body. It is customary for bulk commodities to be discharged from the chamber into an unloading bay formed in the floor between the rails and beneath the railway track. The discharging process is controlled by using a discharge system to regulate the opening and closing of the outlet aperture(s).
Conventional discharge systems typically comprise one or more closable doors that are arranged on the underside of an outlet and are movable between an open position and a closed position. For example, a prior art discharge system may comprise a pair of doors that are arranged on opposing sides of an outlet and extend the length of the outlet. Each door is pivotally mounted to allow for the rotation between a closed position and an open position. When rotated to the closed position, the doors extend across the outlet and form a sealing engagement, thereby covering the outlet such that the discharging of bulk commodities is prevented. When the doors are rotated to the open position, the outlet is uncovered such that unrestricted discharging can occur.
During the discharging process, it has been found that bulk commodities may spill or spread undesirably. For example, when discharging a hopper wagon, bulk commodities may spill laterally and/or longitudinally along the railway track and the surrounding area rather than into the unloading bay. The spillage of bulk commodities is wasteful. The spillage of bulk commodities may impede the operation of the hopper. For example, the spillage on the railway tracks may reduce the engagement between the bogie wheels and railway track and may ultimately lead to the derailment of the hopper wagon. The spillage may obstruct the motion of the doors such that they are unable to open and close properly. The spillage may interfere with other component parts of the hopper or associated apparatus. The spillage of bulk commodities may release unwanted dust or particulates into the atmosphere. Accordingly, railway personnel must regularly inspect the railway track to remove any spillage from a hopper wagon, which is both an expensive and time consuming procedure. Given that hopper wagons may have approximately 20,000 to 30,000 loading/unloading cycles over a lifetime, the spillage of bulk commodities for hopper wagons is a significant problem.